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Valli D, Ooi SA, Scattolini G, Chaudhary H, Tietze AA, Maj M. Improving cryo-EM grids for amyloid fibrils using interface-active solutions and spectator proteins. Biophys J 2024; 123:718-729. [PMID: 38368506 PMCID: PMC10995402 DOI: 10.1016/j.bpj.2024.02.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2023] [Revised: 01/28/2024] [Accepted: 02/13/2024] [Indexed: 02/19/2024] Open
Abstract
Preparation of cryoelectron microscopy (cryo-EM) grids for imaging of amyloid fibrils is notoriously challenging. The human islet amyloid polypeptide (hIAPP) serves as a notable example, as the majority of reported structures have relied on the use of nonphysiological pH buffers, N-terminal tags, and seeding. This highlights the need for more efficient, reproducible methodologies that can elucidate amyloid fibril structures formed under diverse conditions. In this work, we demonstrate that the distribution of fibrils on cryo-EM grids is predominantly determined by the solution composition, which is critical for the stability of thin vitreous ice films. We discover that, among physiological pH buffers, HEPES uniquely enhances the distribution of fibrils on cryo-EM grids and improves the stability of ice layers. This improvement is attributed to direct interactions between HEPES molecules and hIAPP, effectively minimizing the tendency of hIAPP to form dense clusters in solutions and preventing ice nucleation. Furthermore, we provide additional support for the idea that denatured protein monolayers forming at the interface are also capable of eliciting a surfactant-like effect, leading to improved particle coverage. This phenomenon is illustrated by the addition of nonamyloidogenic rat IAPP (rIAPP) to a solution of preaggregated hIAPP just before the freezing process. The resultant grids, supplemented with this "spectator protein", exhibit notably enhanced coverage and improved ice quality. Unlike conventional surfactants, rIAPP is additionally capable of disentangling the dense clusters formed by hIAPP. By applying the proposed strategies, we have resolved the structure of the dominant hIAPP polymorph, formed in vitro at pH 7.4, to a final resolution of 4 Å. The advances in grid preparation presented in this work hold significant promise for enabling structural determination of amyloid proteins which are particularly resistant to conventional grid preparation techniques.
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Affiliation(s)
- Dylan Valli
- Department of Chemistry - Ångström Laboratory, Uppsala University, Uppsala, Sweden
| | - Saik Ann Ooi
- Department of Chemistry and Molecular Biology, University of Gothenburg, Gothenburg, Sweden
| | - Giorgio Scattolini
- Department of Chemistry - Ångström Laboratory, Uppsala University, Uppsala, Sweden
| | - Himanshu Chaudhary
- Department of Chemistry - Ångström Laboratory, Uppsala University, Uppsala, Sweden
| | - Alesia A Tietze
- Department of Chemistry and Molecular Biology, University of Gothenburg, Gothenburg, Sweden
| | - Michał Maj
- Department of Chemistry - Ångström Laboratory, Uppsala University, Uppsala, Sweden.
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Birch J, Cheruvara H, Gamage N, Harrison PJ, Lithgo R, Quigley A. Changes in Membrane Protein Structural Biology. BIOLOGY 2020; 9:E401. [PMID: 33207666 PMCID: PMC7696871 DOI: 10.3390/biology9110401] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Revised: 11/11/2020] [Accepted: 11/12/2020] [Indexed: 12/21/2022]
Abstract
Membrane proteins are essential components of many biochemical processes and are important pharmaceutical targets. Membrane protein structural biology provides the molecular rationale for these biochemical process as well as being a highly useful tool for drug discovery. Unfortunately, membrane protein structural biology is a difficult area of study due to low protein yields and high levels of instability especially when membrane proteins are removed from their native environments. Despite this instability, membrane protein structural biology has made great leaps over the last fifteen years. Today, the landscape is almost unrecognisable. The numbers of available atomic resolution structures have increased 10-fold though advances in crystallography and more recently by cryo-electron microscopy. These advances in structural biology were achieved through the efforts of many researchers around the world as well as initiatives such as the Membrane Protein Laboratory (MPL) at Diamond Light Source. The MPL has helped, provided access to and contributed to advances in protein production, sample preparation and data collection. Together, these advances have enabled higher resolution structures, from less material, at a greater rate, from a more diverse range of membrane protein targets. Despite this success, significant challenges remain. Here, we review the progress made and highlight current and future challenges that will be overcome.
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Affiliation(s)
- James Birch
- Membrane Protein Laboratory, Diamond Light Source Ltd., Harwell Science and Innovation Campus, Didcot OX11 0DE, UK; (J.B.); (H.C.); (N.G.); (P.J.H.); (R.L.)
- Research Complex at Harwell (RCaH), Harwell Science and Innovation Campus, Didcot OX11 0FA, UK
| | - Harish Cheruvara
- Membrane Protein Laboratory, Diamond Light Source Ltd., Harwell Science and Innovation Campus, Didcot OX11 0DE, UK; (J.B.); (H.C.); (N.G.); (P.J.H.); (R.L.)
- Research Complex at Harwell (RCaH), Harwell Science and Innovation Campus, Didcot OX11 0FA, UK
| | - Nadisha Gamage
- Membrane Protein Laboratory, Diamond Light Source Ltd., Harwell Science and Innovation Campus, Didcot OX11 0DE, UK; (J.B.); (H.C.); (N.G.); (P.J.H.); (R.L.)
- Research Complex at Harwell (RCaH), Harwell Science and Innovation Campus, Didcot OX11 0FA, UK
| | - Peter J. Harrison
- Membrane Protein Laboratory, Diamond Light Source Ltd., Harwell Science and Innovation Campus, Didcot OX11 0DE, UK; (J.B.); (H.C.); (N.G.); (P.J.H.); (R.L.)
- Research Complex at Harwell (RCaH), Harwell Science and Innovation Campus, Didcot OX11 0FA, UK
| | - Ryan Lithgo
- Membrane Protein Laboratory, Diamond Light Source Ltd., Harwell Science and Innovation Campus, Didcot OX11 0DE, UK; (J.B.); (H.C.); (N.G.); (P.J.H.); (R.L.)
- Research Complex at Harwell (RCaH), Harwell Science and Innovation Campus, Didcot OX11 0FA, UK
- School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough LE12 5RD, Leicestershire, UK
| | - Andrew Quigley
- Membrane Protein Laboratory, Diamond Light Source Ltd., Harwell Science and Innovation Campus, Didcot OX11 0DE, UK; (J.B.); (H.C.); (N.G.); (P.J.H.); (R.L.)
- Research Complex at Harwell (RCaH), Harwell Science and Innovation Campus, Didcot OX11 0FA, UK
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Li T, Zheng Q, Yu H, Wu D, Xue W, Xiong H, Huang X, Nie M, Yue M, Rong R, Zhang S, Zhang Y, Wu Y, Wang S, Zha Z, Chen T, Deng T, Wang Y, Zhang T, Chen Y, Yuan Q, Zhao Q, Zhang J, Gu Y, Li S, Xia N. SARS-CoV-2 spike produced in insect cells elicits high neutralization titres in non-human primates. Emerg Microbes Infect 2020; 9:2076-2090. [PMID: 32897177 PMCID: PMC7534368 DOI: 10.1080/22221751.2020.1821583] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The current coronavirus disease 2019 (COVID-19) pandemic was the result of the rapid transmission of a highly pathogenic coronavirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), for which there is no efficacious vaccine or therapeutic. Toward the development of a vaccine, here we expressed and evaluated as potential candidates four versions of the spike (S) protein using an insect cell expression system: receptor binding domain (RBD), S1 subunit, the wild-type S ectodomain (S-WT), and the prefusion trimer-stabilized form (S-2P). We showed that RBD appears as a monomer in solution, whereas S1, S-WT, and S-2P associate as homotrimers with substantial glycosylation. Cryo-electron microscopy analyses suggested that S-2P assumes an identical trimer conformation as the similarly engineered S protein expressed in 293 mammalian cells but with reduced glycosylation. Overall, the four proteins confer excellent antigenicity with convalescent COVID-19 patient sera in enzyme-linked immunosorbent assay (ELISA), yet show distinct reactivities in immunoblotting. RBD, S-WT and S-2P, but not S1, induce high neutralization titres (>3-log) in mice after a three-round immunization regimen. The high immunogenicity of S-2P could be maintained at the lowest dose (1 μg) with the inclusion of an aluminium adjuvant. Higher doses (20 μg) of S-2P can elicit high neutralization titres in non-human primates that exceed 40-times the mean titres measured in convalescent COVID-19 subjects. Our results suggest that the prefusion trimer-stabilized SARS-CoV-2 S-protein from insect cells may offer a potential candidate strategy for the development of a recombinant COVID-19 vaccine.
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Affiliation(s)
- Tingting Li
- State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, School of Life Sciences, School of Public Health, Xiamen University, Xiamen, People's Republic of China.,National Institute of Diagnostics and Vaccine Development in Infectious Disease, Xiamen University, Xiamen, People's Republic of China
| | - Qingbing Zheng
- State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, School of Life Sciences, School of Public Health, Xiamen University, Xiamen, People's Republic of China.,National Institute of Diagnostics and Vaccine Development in Infectious Disease, Xiamen University, Xiamen, People's Republic of China
| | - Hai Yu
- State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, School of Life Sciences, School of Public Health, Xiamen University, Xiamen, People's Republic of China.,National Institute of Diagnostics and Vaccine Development in Infectious Disease, Xiamen University, Xiamen, People's Republic of China
| | - Dinghui Wu
- Department of Pulmonary Medicine, The First Affiliated Hospital of Xiamen University, Xiamen, People's Republic of China
| | - Wenhui Xue
- State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, School of Life Sciences, School of Public Health, Xiamen University, Xiamen, People's Republic of China.,National Institute of Diagnostics and Vaccine Development in Infectious Disease, Xiamen University, Xiamen, People's Republic of China
| | - Hualong Xiong
- State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, School of Life Sciences, School of Public Health, Xiamen University, Xiamen, People's Republic of China.,National Institute of Diagnostics and Vaccine Development in Infectious Disease, Xiamen University, Xiamen, People's Republic of China
| | - Xiaofen Huang
- State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, School of Life Sciences, School of Public Health, Xiamen University, Xiamen, People's Republic of China.,National Institute of Diagnostics and Vaccine Development in Infectious Disease, Xiamen University, Xiamen, People's Republic of China
| | - Meifeng Nie
- State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, School of Life Sciences, School of Public Health, Xiamen University, Xiamen, People's Republic of China.,National Institute of Diagnostics and Vaccine Development in Infectious Disease, Xiamen University, Xiamen, People's Republic of China
| | - Mingxi Yue
- State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, School of Life Sciences, School of Public Health, Xiamen University, Xiamen, People's Republic of China.,National Institute of Diagnostics and Vaccine Development in Infectious Disease, Xiamen University, Xiamen, People's Republic of China
| | - Rui Rong
- State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, School of Life Sciences, School of Public Health, Xiamen University, Xiamen, People's Republic of China.,National Institute of Diagnostics and Vaccine Development in Infectious Disease, Xiamen University, Xiamen, People's Republic of China
| | - Sibo Zhang
- State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, School of Life Sciences, School of Public Health, Xiamen University, Xiamen, People's Republic of China.,National Institute of Diagnostics and Vaccine Development in Infectious Disease, Xiamen University, Xiamen, People's Republic of China
| | - Yuyun Zhang
- State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, School of Life Sciences, School of Public Health, Xiamen University, Xiamen, People's Republic of China.,National Institute of Diagnostics and Vaccine Development in Infectious Disease, Xiamen University, Xiamen, People's Republic of China
| | - Yangtao Wu
- State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, School of Life Sciences, School of Public Health, Xiamen University, Xiamen, People's Republic of China.,National Institute of Diagnostics and Vaccine Development in Infectious Disease, Xiamen University, Xiamen, People's Republic of China
| | - Shaojuan Wang
- State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, School of Life Sciences, School of Public Health, Xiamen University, Xiamen, People's Republic of China.,National Institute of Diagnostics and Vaccine Development in Infectious Disease, Xiamen University, Xiamen, People's Republic of China
| | - Zhenghui Zha
- State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, School of Life Sciences, School of Public Health, Xiamen University, Xiamen, People's Republic of China.,National Institute of Diagnostics and Vaccine Development in Infectious Disease, Xiamen University, Xiamen, People's Republic of China
| | - Tingting Chen
- State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, School of Life Sciences, School of Public Health, Xiamen University, Xiamen, People's Republic of China.,National Institute of Diagnostics and Vaccine Development in Infectious Disease, Xiamen University, Xiamen, People's Republic of China
| | - Tingting Deng
- State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, School of Life Sciences, School of Public Health, Xiamen University, Xiamen, People's Republic of China.,National Institute of Diagnostics and Vaccine Development in Infectious Disease, Xiamen University, Xiamen, People's Republic of China
| | - Yingbin Wang
- State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, School of Life Sciences, School of Public Health, Xiamen University, Xiamen, People's Republic of China.,National Institute of Diagnostics and Vaccine Development in Infectious Disease, Xiamen University, Xiamen, People's Republic of China
| | - Tianying Zhang
- State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, School of Life Sciences, School of Public Health, Xiamen University, Xiamen, People's Republic of China.,National Institute of Diagnostics and Vaccine Development in Infectious Disease, Xiamen University, Xiamen, People's Republic of China
| | - Yixin Chen
- State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, School of Life Sciences, School of Public Health, Xiamen University, Xiamen, People's Republic of China.,National Institute of Diagnostics and Vaccine Development in Infectious Disease, Xiamen University, Xiamen, People's Republic of China
| | - Quan Yuan
- State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, School of Life Sciences, School of Public Health, Xiamen University, Xiamen, People's Republic of China.,National Institute of Diagnostics and Vaccine Development in Infectious Disease, Xiamen University, Xiamen, People's Republic of China
| | - Qinjian Zhao
- State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, School of Life Sciences, School of Public Health, Xiamen University, Xiamen, People's Republic of China.,National Institute of Diagnostics and Vaccine Development in Infectious Disease, Xiamen University, Xiamen, People's Republic of China
| | - Jun Zhang
- State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, School of Life Sciences, School of Public Health, Xiamen University, Xiamen, People's Republic of China.,National Institute of Diagnostics and Vaccine Development in Infectious Disease, Xiamen University, Xiamen, People's Republic of China
| | - Ying Gu
- State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, School of Life Sciences, School of Public Health, Xiamen University, Xiamen, People's Republic of China.,National Institute of Diagnostics and Vaccine Development in Infectious Disease, Xiamen University, Xiamen, People's Republic of China
| | - Shaowei Li
- State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, School of Life Sciences, School of Public Health, Xiamen University, Xiamen, People's Republic of China.,National Institute of Diagnostics and Vaccine Development in Infectious Disease, Xiamen University, Xiamen, People's Republic of China
| | - Ningshao Xia
- State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, School of Life Sciences, School of Public Health, Xiamen University, Xiamen, People's Republic of China.,National Institute of Diagnostics and Vaccine Development in Infectious Disease, Xiamen University, Xiamen, People's Republic of China.,The Research Unit of Frontier Technology of Structural Vaccinology of Chinese Academy of Medical Sciences, People's Republic of China
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